Portable, Remote, Fast-Fill Inflator and Nitrogen Converter Unit

ABSTRACT

A portable device for delivering nitrogen to multiple tires includes a gas source and supply line connected to a controller. The device also includes a gas delivery line comprising a manifold with a plurality of outlets in fluid communication with each other. A gas delivery line is operably connected to the controller and a plurality of extension lines with engagement chucks are operably connected to the outlets. The controller controls the supply of gas to the gas delivery line and controls a relief valve for venting the gas delivery line. The device also includes a sensor and a processor connected the controller and sensor which accepts user inputs. The controller, manifold, and processor are affixed to a stand.

RELATED APPLICATIONS

This non-provisional application is a continuation of application Ser.No. 12/355,528 entitled “Portable, Remote, Fast-Fill Inflator andNitrogen Converter Unit”, filed 16 Jan. 2009, which is a division ofapplication Ser. No. 11/447,079, filed on 6 Jun. 2006 entitled“Portable, Remote, Fast-Fill Inflator and Nitrogen Converter Unit” nowU.S. Pat. No. 7,624,774, which claims priority benefit of provisionalapplication Ser. No. 60/687,326 entitled “Portable, Remote, Fast-FillInflator and Nitrogen Converter Unit,” filed 6 Jun. 2005, the entiretyof each is incorporated herein by reference.

BACKGROUND

Pneumatic tires for automobiles, aircraft and other vehicles havetraditionally been inflated by compressed ambient air. Generally,compressed air works well with bicycle tires, tractor tires and evenstandard automobile tires run at relatively low speeds where exactingtire balance and consistent tire pressure is not critical. In the caseof uses such as race cars, dragsters, and high altitude aircraft,compressed ambient air is not a satisfactory medium for inflating tiresfor a variety of reasons.

When compressed air is introduced into a tire via a compressor open tothe ambient atmosphere, water vapor and other impurities are introducedinto the tire in the same proportions as they occur in the ambient air.With all of the moisture and other impurities present, air volume in thetire fluctuates fairly widely with temperature, particularly due to themoisture changing from liquid to vapor form and from vapor to liquidform as temperatures in the tire change. In addition, tire pressures mayvary from tire to tire which may also possess deleterious results.

Pressure of air in tires inflated with compressed ambient air willchange about 1 psi for every 10 degree Fahrenheit change in temperature.Thus, a tire inflated at 60 degrees Fahrenheit will be substantiallyunder inflated at 20 degrees due to the combined effects of temperaturein reducing gas pressure and moisture condensing out of the air withinthe tire. Conversely, as temperatures increase to 90 degrees Fahrenheit,the tire will be substantially over inflated due to the water beingvaporized and the attendant increase in air pressure due to temperature.These under or over inflation conditions can adversely affect rollingfriction of tires on pavement, thus decreasing gas mileage. Tire wear isalso substantially increased when tires are not inflated to amanufacturer's recommendations. Handling problems may be aggravated bytire pressure differential between front and back tires and/or side toside.

Water vapor within tires may also induce rust within steel beltedradials, which further reduces tire life. Furthermore water vaporintroduced into a tire in a high altitude jet airplane, for example,will condense and then freeze thereby forming ice crystals whichgenerally fall to the bottom of the tire as it lies stationary in thewheel well of the airplane. When an airplane lands, the tires mustaccelerate virtually instantly from rest to more than 150 miles perhour. As a result, ice crystals in the tire can create a substantialimbalance. As the tire accelerates, the ice crystals are thrown aroundthe rolling tire by centrifugal force, leading to further imbalance,increased internal wear, and an increased likelihood of tire blow-outs.In the case of race cars and dragsters, since the water vapor introducedinto the tire condenses and vaporizes at unpredictable times, condensedwater within the tire lags behind the column of air within the tire asthe tire is rapidly accelerated. Furthermore, as the race car tires spinat high speed, considerable heat builds up in the tires themselves, thusconsiderably increasing the internal tire pressure due to the expansionof the water vapor.

In order to eliminate these problems, operators and owners of race cars,space shuttle transport vehicles, earthmoving and mining equipment andcommercial and military high altitude aircraft often inflate their tireswith compressed nitrogen or another generally non-reactive andnon-combustible gas such as argon or sulfur hexafluoride. Nitrogen is anideal gas for such a purpose since it is chemically non-reactive,non-combustible, non-flammable and non-corrosive. Furthermore, when dry,nitrogen gas is relatively stable in volume through a wide range oftemperatures. For example, the specific volume of a quantity of drynitrogen gas at 1 atmosphere of pressure varies less than 13% in a rangeof −10 degrees F. to +116 degrees F. Thus, the use of nitrogen toinflate a pneumatic tire offers a large reduction in fluctuations ofinternal tire pressure due to temperature variations over those whichoccur when moisture laden compressed ambient air is used. Furthermore,since nitrogen is stored in pressurized tanks under controlledconditions, the nitrogen gas can be dried and purified as it is placedinto the tank, thus minimizing moisture and other impurities transferredinto the tire.

However, when new or repaired tires are first placed on a wheel, theymust be inflated under high pressure to get the tire bead to seat on thewheel rim. In order to accomplish this compressed ambient air must beused. Once the tire is inflated and properly seated on the wheel rim,the compressed air is bled off via a tire's Schrader spring loadedvalve, and a source of compressed nitrogen is then attached to the tirevalve to re-inflate the tire. With this method, the tire's internalpressure is simply returned to ambient pressure before being filled withnitrogen. This air at ambient pressure in the tire having a quantityequal to the internal volume of the tire. Along with the quantity of airleft in the tire, moisture and other gaseous impurities are present inthe tire in the same proportion as they are found in the ambientatmosphere. When the dry, purified nitrogen is introduced into the tireunder pressure, it mixes with the air, moisture and other impuritiesalready present in the tire as the tire is inflated. The inflated tireis thus filled with a quantity of air including attendant moisture andother impurities and a larger quantity of nitrogen, thus repeating,albeit at a reduced level, the problems associated with the use ofambient compressed air.

It is clear that a need exists for a tire inflation apparatus and methodwhich avoids these problems of the prior art. Such a tire inflationapparatus should preferably inflate tires with compressed, purified anddried gas, such as nitrogen, to a manufacturer's recommended tirepressure while minimizing or eliminating moisture and other impuritiesin the tire.

In order to obviate the deficiencies in the prior art, it is an objectof the present subject matter to present a novel portable gas deliverydevice. The device includes a gas source and supply line connected to acontroller. The device also includes a gas delivery line comprising amanifold with a plurality of outlets in fluid communication with eachother. A gas delivery line is operably connected to the controller and aplurality of extension lines with engagement chucks are operablyconnected to the outlets. the controller controls the supply of gas tothe gas delivery line and controls a relief valve for venting the gasdelivery line. The device also includes a sensor and a processorconnected the controller and sensor which accepts user inputs. Thecontroller, manifold and processor are affixed to a stand.

It is also an object of the present subject matter to present a novelmethod of ensuring pressure equalization between multiple tires duringevacuation and inflation of the tires. The method includes providing aplurality of supply hoses in fluid communication with each other,attaching each of the supply hoses to a corresponding valve stem locatedon the tires, and supplying pressurized gas from a gas source to thetires via the supply hoses. The method further includes monitoring andcontrolling a gas characteristic of the pressurized gas in the of thesupply hoses to inflate the tire to a predetermined pressure so as toensure pressure equalization between each of the tires.

It is a further object of the present subject matter to present a novelmethod for evacuating and inflating a pneumatic tire. The methodincluding opening a relief valve on a gas supply hose to vent the supplyhose to atmosphere, closing the relief valve, and supplying pressurizedinert gas from a gas source to the tire through the gas supply hose toinflate the tire with a first predetermined amount of inert gas. Themethod also includes opening the relief valve to vent the gas supplyhose to atmosphere, closing the relief valve, and supplying pressurizedinert gas from the gas source to the tire through the gas supply hose toinflate the tire with a second predetermined amount of inert gas.

These objects and other advantages of the disclosed subject matter willbe readily apparent to one skilled in the art to which the disclosurepertains from a perusal or the claims, the appended drawings, and thefollowing detailed description of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are representations of a portable gas delivery deviceaccording to an embodiment of the present subject matter.

FIG. 2 is a flow chart representation of a method of ensuring pressureequalization between multiple tires according to an embodiment of thepresent subject matter.

FIG. 3 is a flow chart representation of a method of evacuation andinflating a pneumatic tire according to an embodiment of the presentsubject matter.

FIG. 4 is an illustrative chart of gas characteristics experienced by atire during the method of FIG. 3.

DETAILED DESCRIPTION

Referring to the drawings, and particularly FIGS. 1A and 1B, a tireevacuation and inflation apparatus is illustrated. The tire evacuationand inflation apparatus 1 includes a frame 2 mounted on an axle 3 with apair of wheels 4 attached thereto. The frame 2 includes a handle 5 onthe rear thereof which allows the frame 2 to be easily tilted backwardsuch that the weight of the apparatus 1 is resting on the wheels 4. Abrace 7 is attached to the bottom of the frame 2 and extends across thewidth thereof to provide stable support for the frame 2. A tank 14containing a quantity of pressurized, dried and purified gas, such asnitrogen, sulfur hexafluoride or argon is also positioned within theframe 2. A pressure regulator 15 is attached to an outlet 21 of the tank14 which outlet is opened and closed via a hand operated valve 22. Anitrogen supply hose 23 is connected between the regulator 15 and anoutlet manifold 24. A first end of each of a plurality tire supply hosesor extension lines 33 is attached to an outlet 26 of the outlet manifold24 with a second end being attached to a standard spring closed tirevalve chuck 35. The extension lines 33 are preferably pre-coiled linesand connect to the outlets with quick disconnect fittings 31.Additionally, the frame 2 may have a plurality of engagement chuckretainers (not shown) that secure the engagement chucks 35 duringstorage. The engagement chuck retainers are preferably positioned on theupper portion of the frame 2 or stand.

The manifold 24 may also include a connection 27 adapted to receive agas supply line from a remote gas supply in lieu of the gas supply tank14. The plurality of outlets 26 may be each in fluid communication withone another. A controller 25 is controls the supply of gas from the gassupply line 23 to the manifold 24 and further controls a relief valve 43that vents the gas of the delivery lines 33 and manifold 24. Thecontroller 25 is preferably an electromechanical valve.

A sensor 29 is located downstream of the controller 25 and is operablyconnected to a processor 28 which operates to control the controller 25and relief valve 43. The sensor can be any type of appropriatetransducer such as strain or piezoelectric gages for pressure, orthermocouples for temperature. The processor 28 can be any one or moreof a microprocessor, application specific integrated circuit, or logicalcircuit. The processor 28 controls the controller 25 based on gascharacteristics detected by the sensor 29 and/or a predetermined dutycycle stored in a memory of the processor 28. The gas characteristicsmay include, but are not limited to, gas flow rate, gas pressure, gastemperature, gas volume or specific gas concentration. The processor 28may also include an internal timer for implementing the predeterminedduty cycle. The predetermined duty cycle includes at least one inflationstage, a deflation stage, and a second re-inflation stage. Dependingupon the desired concentration of nitrogen in the tires, thepredetermined duty cycle may include several successiveinflation-deflation cycles. For every inflation-deflation cycle theconcentration of nitrogen or other inert gas would increase.

To operate the processor 28 and controller 25, an electrical powerinterface 42 is located on the frame 2. The electrical power interfacecan be a connection to battery terminals of a battery (not shown) thatattaches to the frame 2 or an AC plug on the end of an extension cord asshown in FIG. 1. The processor 28 may also include an input device 45 toreceive user input as well as a display 44 to assist with the entry ofuser inputs. The input device 45 may be a keyboard, touch screen orother similar device.

A tire (not shown) to be inflated originally, is first seated on a wheelrim by being inflated with compressed ambient air in a well knownmanner. Depending upon the type of tire, the tire is either seated onthe wheel by pressure on a peripheral “bead” which engages a groove inthe wheel or, in the case of some racing and high performanceapplications, the tire may actually be bolted to the wheel rim toprevent slippage. In either case, the inflated, seated tire is thendeflated as described in a method discussed hereafter or in a standardmethod, by removing the Schrader valve from the tire valve stem, orholding the Schrader valve open with some type of tool. Once deflated,the tire remains filled with a quantity of ambient air at atmosphericpressure. The Schrader valve, if removed, is then replaced. The tireevacuation and inflation apparatus 1, if not already attached, may thenbe attached to the tire valve stem by connecting the chuck 35 to thetire valve stem.

Nitrogen (or another suitable pressurized gas) is then supplied to thetire via the nitrogen supply hose 23, the controller 25, the manifold 24and the tire supply hose 33. The controller 25 is preferably set by theprocessor to supply nitrogen to pressurize the tire to the desiredinternal tire pressure, such as 32 psi for a standard passenger tire or6 to 7 psi for large bias ply rear tires used on dragsters. Thecontroller 25 may be initially set at a pressure considerably higherthan the desired internal tire pressure to ensure that the tire willinflate relatively rapidly to the desired pressure.

The pressure of the gas within the tire will change with changes intemperature of the gas. If the tire is filled to a recommended pressurewith cooled nitrogen (or other gas utilized), the tire pressure willsubsequently increase as the temperature of the nitrogen rises toambient temperature and will further increase during operation of thevehicle resulting in over-inflation of the tire.

In a preferred embodiment, the temperature, as well as the pressure, ismonitored and controlled to fill the tire to a predetermined pressure ata predetermined temperature to thereby minimize problems associated withover and under inflation of the tires due to changes in the tirepressure as the temperature of the gas in the tires changes during use.Of course, other gas characteristics may be monitored and controlledsuch as gas concentration, flow rate, volume and other known gascharacteristics.

The tire is thus inflated by the nitrogen tank 14 and regulator 15 to apreferred tire pressure at a preferred temperature, thus yielding a tirewhich is inflated solely with a purified, dried gas. The tire, thusinflated, will not be subject to the wide swings in tire pressure withtemperature exhibited by tires inflated by traditional methods.

FIG. 2 is a flow chart representation of a method to ensure pressureequalization between a plurality of tires during evacuation andinflation of the tires. A plurality of supply hoses in fluidcommunication with each other is provided and each of the supply hosesis attached to a corresponding valve stem on the plurality of tires asrepresented in Block 201 and 203 respectively. In a passenger car, fourtire supply hoses can be supplied and all four tires simultaneouslyfilled with nitrogen. In vehicles where the tire sets, e.g., front andback tire sets, require different pressures, each set may be filledindividually, i.e., filing the front set and then filling the back setin a passenger car.

Pressurized gas from a gas source, such as the portable tank or from asupply line, is then applied to the plurality of tires via the manifold24 and tire supply hoses 33 as represented in Block 205. The processor28, via sensor 29 and controller 25, monitors and controls a gascharacteristic of the pressurized gas, such as temperature, pressure,concentration or volume as represented in Block 207. The result isinflation of the plurality of tires to a predetermined pressure whereequalization of pressure exists between each of the plurality of tiresdue to their communication with the manifold 24.

In a preferred embodiment, a user inputs data, such as the number oftires and the identity, e.g., type, size or model of the tire, or simpledesired pressure into a processor. The processor may then retrieve tiredata, if not provided by the user, from an internal or external databaseas a function of the identity of the tire. The processor alsoadvantageously determines the appropriate predetermined pressure. Forexample, the user inputs a tire size such as 235 R15, the processor andthen retrieves data, such as the recommended pressure or tire volume.The processor, by monitoring a gas characteristic such as pressure, canthen apply pressurized gas until the predetermine pressure is reached,or in an alternative embodiment may determine a pressure at themonitored gas temperature which would result in the recommended pressureupon the gas in the tire reaching ambient temperature. In either manner,since all of the tires are in fluid communication with each otherthrough the manifold and extension lines, all the tires would haveidentical pressure, which, as described previously, is beneficial toperformance.

FIG. 3 is a flow chart for a method of evacuating and inflating apneumatic tire. This method is applicable to tires currently filled withair and making a transition to nitrogen. The extension lines 33 via thechuck 35 are connected to the valve stems of the tires to be switched tonitrogen as represented in Block 300. A relief valve 43 in fluidcommunication with the manifold 24 is then opened to vent the tiresupply hose 33 to atmosphere as represented in Block 301. This ventingallows the majority of air in the tires to be evacuated from the tires.The relief valve is then closed when the pressure in the tires reachatmospheric pressure as represented in Block 303. Pressurized nitrogenor other inert gas is then supplied from a gas source to the tirethrough the gas supply hose as represented in Block 305. The nitrogen issupplied to inflate the tires until a first predetermined amount ofnitrogen is supplied to the tires or until a predetermined pressure isreached. This cycle is then repeated opening the relief valve to ventthe gas supply hose to atmosphere, closing the relief valve, andsupplying pressurized inert gas from the gas source to the tire throughthe manifold 24 and tire supply hose 33 to inflate the tire with asecond predetermined amount of nitrogen or second predetermined pressureas represented in Block 307. The second predetermined amount of nitrogenand the second predetermined pressure need not be different from thefirst predetermined amount and pressure. This cycle can be repeatedseveral times as part of a duty cycle or until a threshold is reached.

Table 1 illustrates the gas characteristics in the tire using the methodof FIG. 3. These gas characteristics are also shown graphically in FIG.4. For ease of illustration, air is approximated as 80 percent nitrogenand 20 percent oxygen.

TABLE 1 Gage Volume (standard Nitrogen/oxygen Steps Pressure (psi)atmosphere) Concentration (%) 1. Opening the 35 10   80/20 relief valve2. Closing the 0 1   80/20 relief valve 3. Supplying Gas 0 1   80/20 4.Opening the 35 10   98/02 relief valve 5. Closing relief 0 1   98/02valve 6. Supplying Gas 0 1   98/02 Final 35 10 99.8/0.2

As seen in Table 1 and FIG. 4, the method results in the desiredconcentration at 99.8 percent nitrogen. The final concentration can befurther increased by repeating the cycle. The pressure and volume inTable 1 are simplified and made consistent for ease of illustration.Additionally, rather than relying on pressure, volume or concentration,a timed duty cycle can be utilized which would provide similar results.The component periods of the duty cycle can be determined by the averageflow rate from the supply hose, volume of tires and desired pressure.Such calculations should be readily apparent to those skilled in thepertinent art.

An embodiment of the present subject matter, upon attachment to allserviced tires and engagement of procedure, vents all tires toatmosphere until a 3 psi manifold and thus internal tire pressure isreached, so as not to “break” the tire bead or damage the tire casing.The tires, as discussed above, are then inflated to a preprogrammedpressure value of nitrogen. The tires are again deflated, vented toatmosphere to approximately 3 psi, and then finally re-inflated to apredetermined pressure value. Upon completion of this procedure, whichmay be audibly indicated, all of the tires are equally inflated to thecommon manifold pressure and all tires, because of this “purge” or“washout” process, have a nitrogen purity in excess of a desirable 95%minimum in-the-serviced-tire purity target. As noted previously, withoutthis dilution and washing cycle, because of the volume of air an emptytire contains, even inflation with 100% nitrogen will not yield a puritylevel above the 95% target.

An important aspect of the present subject matter is the ability toinflate multiple tires at a single time while ensuring equal pressure inthe tires. As noted previously a manifold maintains fluid communicationbetween each of the supply hoses and thus each of the multiple tires.

Another aspect of the present subject matter is the ability to replacethe air in a tire with nitrogen automatically without the use of avacuum pump as needed in other prior art devices.

A further aspect of the present subject matter can include independentlysensing gas characteristics at each of the tire supply hoses withassociated sensors. The data from the sensors may be processed to ensureeach tire is equalized with the other tires.

In a further aspect of the present subject matter, the system may becoin-operated for use in retail services, such as at remote air stationslocated at shopping centers, gas stations, etc.

A further favorable aspect of the present subject matter is that thesystem provides means of conversion to nitrogen for 1-6 tiressimultaneously. (4 tires on the ground and the spare in the trunk or 6tires on so equipped trucks, or any other combination). This isadvantageous with respect to time and facilities, and the vehicle is notrequired to be lifted.

An additional aspect afforded by the present subject matter is thesystem does not require the removal of the tire valve core or removal ofthe tire/wheel from the vehicle. The entire operation requires only 60seconds of hands-on time, again representing a significant reduction intime, labor and capital costs.

The mobility of the present subject matter may also be favorablyincreased with the use of an onboard compressed nitrogen tank andonboard battery as opposed to being tethered to a nitrogen generator andelectrical power source. The use of an onboard rechargeable battery andnitrogen supply enables the system to be self contained and allowsservicing of vehicles at any location.

While preferred embodiments of the present inventive system and methodhave been described, it is to be understood that the embodimentsdescribed are illustrative only and that the scope of the embodiments ofthe present inventive system and method is to be defined solely by theappended claims when accorded a full range of equivalence, manyvariations and modifications naturally occurring to those of skill inthe art from a perusal hereof.

1. A nitrogen-for-air substitution device comprising: a nitrogen gassource; a gas supply line operably connected between said nitrogen gassource and a controller; a gas delivery line comprising a manifold witha plurality of outlets that are in fluid communication with each other,said gas delivery line operably connected to said controller; aplurality of extension lines each comprising an engagement chuck at adistal end thereof, wherein each extension line is operably connected toa corresponding one of said plurality of outlets; said controlleroperable to control the supply of gas from said gas supply line to saidgas delivery line and further operable to control a relief valve forventing said gas delivery line; a processor operably connected to saidcontroller and operable to accept user input; and a stand wherein thecontroller, manifold, and processor are affixed thereto, wherein theprocessor controls the controller based on a predetermined duty cycle,said predetermined duty cycle comprising at least an evacuation cyclefollowed by an inflation cycle.
 2. The device of claim 1 wherein saidprocessor controls said controller based on said predetermined dutycycle and on user input.
 3. The device of claim 1 wherein the gas sourceis a gas tank or a gas generator.
 4. The device of claim 1 wherein theprocessor comprises a visual display and a user input device.
 5. Thedevice of claim 1 wherein the processor comprises a databasecorresponding to the desired concentration of nitrogen with thepredetermined duty cycle.
 6. A device for replacing a first gas mixturecontained within each of a plurality of tires with a second gas mixturehaving a predetermined concentration of nitrogen, wherein the deviceperforms at least one set of evacuations of the tires and charging ofthe tires with a third gas mixture predominantly comprising nitrogen toobtain the second gas mixture, the device comprising: a nitrogen gassource; a gas supply line operably connected between said nitrogen gassource and a controller; a gas delivery line comprising a manifold witha plurality of outlets that are in fluid communication with each other,said gas delivery line operably connected to said controller; aplurality of extension lines each comprising an engagement chuck at adistal end thereof, wherein each extension line is operably connected toa corresponding one of said plurality of outlets; said controlleroperable to control the supply of gas from said gas supply line to saidgas delivery line and further operable to control a relief valve forventing said gas mixture in the tires; a processor operably connected tosaid controller and operable to accept user input; and a stand whereinthe controller, manifold, and processor are affixed thereto, wherein theprocessor controls the controller based on a predetermined duty cycle.7. The device of claim 6 wherein said processor controls said controllerbased on said predetermined duty cycle and on user input.
 8. The deviceof claim 6 wherein the gas source is a gas tank or a gas generator. 9.The device of claim 6 wherein the processor comprises a visual displayand a user input device.
 10. The device of claim 6 wherein the processorcomprises a database corresponding to the desired concentration ofnitrogen with the predetermined duty cycle.
 11. A method of evacuatingand inflating a plurality of pneumatic tires comprising: opening arelief valve on a manifold connected to a plurality of gas supply hosesto vent the supply hoses to atmosphere; closing the relief valve;supplying pressurized inert gas from a gas source to the tires throughthe manifold to the gas supply hoses to inflate the tires to a firstpredetermined characteristic of inert gas; opening the relief valve tovent the gas supply hoses to atmosphere; closing the relief valve;supplying pressurized inert gas from the gas source to the tires throughthe gas supply hoses to inflate the tire to a second predeterminedcharacteristic of inert gas; and determining the first predeterminedcharacteristic and the second predetermined characteristic of inert gasbased on a predetermined duty cycle.
 12. The method of claim 11 whereinsaid determining the first predetermined characteristic and the secondpredetermined characteristic of inert gas is based on a predeterminedduty cycle and on user input.
 13. The method of claim 11 wherein the gassource is a gas tank or a gas generator.
 14. The method of claim 11wherein the relief valve is closed at a manifold pressure of 3 psi. 15.The method of claim 11 wherein the gas characteristic is selected fromthe group consisting of pressure, volume, gas concentration, andcombinations thereof.
 16. The method of claim 11 wherein the steps ofopening the relief valve, closing the relief valve, and supplyingpressurized inert gas are repeated until a concentration of the inertgas in the tires reaches a predetermined threshold.
 17. The method ofclaim 16 wherein the concentration is based at least on a sampling ofthe gas vented to atmosphere.
 18. The method of claim 16 wherein the gassource is a gas tank or a gas generator.
 19. The method of claim 16wherein the relief valve is closed at a manifold pressure of 3 psi. 20.The method of claim 16 wherein the gas characteristic is selected fromthe group consisting of pressure, volume, gas concentration, andcombinations thereof.